[cxx-abi-dev] Mangling sizeof

[John H. Spicer]

On Mar 11, 2009, at 12:34 PM, Jason Merrill wrote:

> Jason Merrill wrote:
>> If we're dropping type stubs, that reintroduces the issue of what  
>> to do with function parameters.  I think it may still make sense to  
>> use type stubs for them; the name of the parameter is not part of  
>> the signature, and I don't think it's possible, given two  
>> parameters of the same type, for it to make a difference which one  
>> you use in a decltype/sizeof expression.  Alternatively, we could  
>> just introduce a mangling for "function parameter N".  Which might  
>> be simpler.
>
> On the other hand, I am sorry to give up the property that
>
>  decltype (*(T*)0 + *(T*)0) f (T t);
> and
>  auto f(T t) -> decltype (t + t)
>
> have the same signature.  Maybe just use type stubs for function  
> parameters and *(T*)0?
>
>

If your program uses both forms of that declaration it is already ill- 
formed because the declarations are functionally equivalent but not  
equivalent by the rules in 14.5.6.1.

John.